The environmental group Greenpeace released this image on May 30, 2006, as part of its protest of tuna "ranches," a practice that rounds up wild fish to be fattened before they are harvested.

Experts say the bluefins are at risk of being fished to extinction, but a lack of data on the fishes' breeding and feeding habits has complicated conservation efforts.

Now a set of new studies is using data from high-tech satellite tags to offer insight on the bluefin's migrations, helping scientists craft better protections for the commercially important species (read "Tagged Tuna Reveal Migration Secrets" [August 13, 2007]).